Naoki Yoshimura

Pharmacological activation of Piezo1 by Yoda1 suppresses mechanosensitive urothelial ATP release through Ca ²⁺ -dependent connexin hemichannel closure and Ca ²⁺ -independent mechanisms. In BOO rats, intravesical Yoda1 reduces elevated ATP levels and attenuates bladder overactivity without impairing voiding function, identifying Piezo1 as a novel therapeutic target for BOO-induced lower urinary tract dysfunction.

Purpose: We aimed to assess the effects of electrical stimulation of the L3–4 spinal cord containing the lumbar spinal coordinating center (LSCC) for neurogenic lower urinary tract dysfunction (NLUTD) in mice with spinal cord injury (SCI).Methods: Male mice were divided into spinal cord intact (SI) and SCI groups. Two electrodes were placed over the epidural surface of the L3–4 spinal cord for electrical spinal cord stimulation (SCS). SCS was initiated when the intravesical pressure of voiding bladder contractions began rising. Cystometrograms (CMG) and external urethral sphincter (EUS)-electromyography (EMG) were recorded before, during and after SCS to examine the effects of SCS on CMG and EUS-EMG parameters in each group.Results: In SI mice, significant differences in CMG parameters were not found after SCS compared to pre-SCS values. However, in SCI mice, the ratio of the voided volume to bladder filling volume was significantly higher after SCS compared to pre- SCS values (P<0.001). Additionally, SCI mice after SCS showed a significantly lower nonvoiding contraction number (P=0.017) and a shorter intercontraction interval (P=0.007) compared to those without SCS. EUS-EMG parameters in SI mice without and with SCS showed no significant differences in the ratio of active phases (AP) to silent phases (SP). In contrast, SCI mice with SCS had a significantly lower AP to SP ratio compared to those without SCS (P<0.001).Conclusions: SCS applied to the L3–4 spinal cord can improve detrusor sphincter dyssynergia by increasing EUS relaxation to mitigate inefficient voiding as well as detrusor overactivity in SCI. Restoration of the LSCC function by SCS could be a therapeutic modality to improve NLUTD after SCI.

Purpose: To investigate the adenosine receptor (AR) mechanism underlying bladder outlet obstruction (BOO)‐related bladder dysfunction, we examined the expression level of AR subtypes in bladder tissues, and the effects of AR subtypes A2B & A3 modulation on bladder activity using male BOO rats, and Dahl rats with A2B receptor deletion. Materials and Methods: BOO was induced by partial ligation of the proximal urethra in male Sprague‐Dawley rats. At 4 weeks after BOO, conscious cystometrograms (CMG) were performed with the urethral ligature being intact. The effects of AR A3 agonist (2CL‐IB‐MECA) and AR A3 antagonist (MRS3777) were examined by intravesical administration. Furthermore, we examined the difference of bladder function of AR subtypes between AR A2B knockout (A2B‐KO) and wild‐type groups of male Dahl rats. mRNA levels of AR subtypes in bladder tissues were also analyzed. Results: BOO versus sham rats showed heavier bladder weights, higher contraction amplitudes, and increased numbers of non‐voiding contractions (NVCs) during the filling phase. In the bladder mucosa – but not the detrusor ‐ of BOO versus sham rats, mRNA expression levels of A2A and A3 AR were significantly increased, while A2B levels were significantly decreased. In BOO rats, an A3 antagonist (MRS 3777; 10 and 100 μM) had no effect on CMG parameters. However, a high dose of an A3 agonist (2CL‐IB‐MECA; 100 μM) significantly increased NVCs ( p = 0.0034), an effect that was blocked by the A3 antagonist. Additionally, compared to wild‐type rats, A2B‐KO rats showed a significant increase in the number of NVCs ( p = 0.0039). Conclusions: A2B AR down‐regulation in BOO rats and A2B deletion in Dahl rats could contribute to the development of bladder overactivity. Moreover, a high‐level of exogenous activation of A3 ARs might exacerbate bladder overactivity in BOO.

Background: Benign prostatic hyperplasia (BPH) is the most common disease in aging males. BPH growth is androgen‐dependent, and it appears that androgens preferentially stimulate the growth of BPH as compared to normal prostate. The mechanism of preferential androgen stimulation of BPH growth is not clear. Our previous studies suggest that primary BPH stromal cells, but not the paired normal adjacent prostate (NAP) stromal cells from the same patients, could stimulate prostatic epithelial cell proliferation in 3D co‐culture. However, whether androgen regulation of prostatic stromal cells is altered in BPH nodules is not clear. Methods: Paired BPH and NAP primary stromal cells were prepared from the same patients. Early passage paired BPH and NAP primary cells were treated with androgens and/or antiandrogens for RNA‐seq analysis. RNA‐seq data were analyzed using principal component analysis (PCA) and functional enrichment analysis. Conditioned medium of the paired BPH and NAP primary cells in the presence or absence of androgens were used in three‐dimensional (3D) culture of benign prostatic epithelial cells. Results: RNA‐seq data analysis suggests that androgen‐induced gene expression in BPH primary stromal cells is heightened compared to paired NAP stromal cells. AR activation in BPH stromal cells appears to enhance cellular motility, vascular and extracellular matrix remodeling, and paracrine signaling, while simultaneously modulating cell cycle and metabolic processes. Compared to regular BPH stromal conditioned medium, conditioned medium of androgen‐stimulated BPH stromal cells further enhanced prostatic epithelial cell proliferation in 3D culture. In contrast, medium of NAP stromal cell culture conditioned in the presence of androgen had no significant effect on prostatic epithelial cell proliferation in 3D culture. Conclusions: Our findings suggest that androgen stimulation of prostatic epithelial cell growth via paracrine prostatic stromal signaling is enhanced in BPH and is associated with heightened androgen‐responsiveness of BPH stromal cells.

The etiology of IC/BPS is multifactorial; thus, pathophysiology‐based phenotyping is needed for tailored treatments of IC/BPS patients. In this regard, it is now generally agreed that, when focusing on inflammatory responses in the bladder mucosa, IC/BPS is divided into two major phenotypes. One is “interstitial cystitis (IC),” which is a chronic inflammatory disorder with Hunner lesions, and the other is “bladder pain syndrome (BPS),” in which inflammatory changes are minimal without Hunner lesions. However, as another important pathophysiological change in the IC/BPS bladder, angiogenetic responses including overexpression of angiogenic growth factors, such as platelet‐derived endothelial cell growth factor (PD‐ECGF), vascular endothelial growth factor (VEGF), and CD31 (platelet endothelial cell adhesion molecule; PECAM‐1), have been shown to correlate with symptom severity in Hunner‐type IC and non‐Hunner IC/BPS patients. In addition, previous studies in IC/BPS patients showed that glomerulations or mucosal bleeding during hydrodistension occur due to the rupture of bladder mucosal capillary vessels in association with PD‐ECGF and VEGF overexpression. Furthermore, upregulation of angiogenic factors and their signaling pathways has been detected in animal models of IC/BPS induced by bladder inflammation or psychological stress. Thus, angiogenic factor overexpression and immature microvessel formation in the bladder mucosa could be another important diagnostic criterion in addition to the inflammatory status for further phenotyping of IC/BPS.

This study shows that selective activation of the imidazoline-2 receptor improves both detrusor overactivity and detrusor-sphincter dyssynergia after spinal cord injury. Systemic and intrathecal administration of 2BFI produced coordinated actions in the spinal cord and lower urinary tract, including enhanced relaxation of the external urethral sphincter, reduced inflammation mediated by C-fiber afferents, and direct relaxation of bladder smooth muscle, indicating a promising therapeutic target.

Inhibitory control of external urethral sphincter motor neurons (EUS‐MNs) in the spinal dorsolateral nucleus (DLN), which corresponds to a portion of Onuf's nucleus in humans, is essential for normal micturition by inducing EUS relaxation during voiding; yet synaptic mechanisms remain poorly characterized. Using neonatal mice P8‐P12, we developed a slicing technique—cutting spinal cords at 150° from the coronal plane (30° from the horizontal plane in the agarose block), for maximizing EUS‐MNs captured per slice. Using transgenic mice co‐expressing channelrhodopsin‐2 in inhibitory interneurons (VGAT‐ChR2) and GFP in cholinergic neurons (ChAT‐GFP), we investigated inhibitory synaptic transmission onto EUS‐MNs. Optogenetic activation evoked robust inhibitory postsynaptic potentials (IPSPs), classified as sustained or transient based on temporal profiles. Pharmacology revealed that sustained IPSPs contained both glycinergic and GABAergic components, while GABAA receptors predominantly mediated transient IPSPs. Strychnine (1 μM) selectively blocked glycinergic transmission, while bicuculline (10 μM) eliminated GABAergic components. Insensitivity to glutamatergic antagonists (CNQX and AP5) confirmed purely inhibitory responses. Our findings demonstrate segregation of inhibitory inputs onto EUS‐MNs, with glycinergic and GABAergic transmission contributing to sustained and transient inhibition, respectively, establishing the methodological foundation for investigating inhibitory circuit dynamics in pathological conditions such as spinal cord injury with deficient inhibitory control.

Purpose This study aimed to characterize the time-dependent changes in lower urinary tract function in a rat model of partial bladder outlet obstruction (BOO) using noninvasive techniques, including uroflowmetry and ultrasound imaging. Methods Eight-week-old male rats underwent partial ligation of the urethra to induce BOO. Voiding behavior was assessed preoperatively and at 1, 2, and 4 weeks postoperatively using metabolic cages. Urine flow rate was calculated based on changes in voided volume over time. Average flow rate, maximum flow rate, and voiding time were derived from these metabolic cage data. Bladder capacity and wall thickness were evaluated by high-resolution ultrasonography. Results Voiding frequency significantly increased at 1, 2, and 4 weeks compared to preoperative values. Mean voided volume per micturition was significantly reduced at 2 weeks. Urinary flow curves showed a sawtooth-like pattern, suggestive of external urethral sphincter bursting that is a characteristic of rat voiding. The maximum flow rate significantly decreased at 1 week postoperatively and remained reduced through 4 weeks. Mean flow rate was significantly decreased at 2 weeks, while voiding time showed a tendency to increase, although the difference was not statistically significant. Ultrasonography revealed significant increases in maximum bladder volume at 2 and 4 weeks and in anterior bladder wall thickness at 4 weeks. Conclusions This study demonstrated the feasibility of noninvasively monitoring time-dependent changes in rats with BOO. These findings could be extrapolated to the pathophysiological process during the bladder compensation phase in human BOO.

Aims: We examined the role of subtypes of adenosine receptors in bladder dysfunction and changes in the adenosine receptor expression in the bladder using male rats with partial bladder outlet obstruction (BOO).Methods: In Sprague‐Dawley rats (male 8‐weeks old), BOO was produced by a partial ligation of the urethra along a metal rod of a 1.2 mm outer diameter. Control rats underwent sham operation. Awake cystometrograms (CMG) were first recorded during saline instillation, and then an adenosine A1 receptor agonist (CCPA, 4.1 μM), an adenosine A2A antagonist (ZM241385, 15 μM), or inosine (1 mM) were applied intravesically in sham and BOO rats. In addition, mRNA levels of adenosine receptor subtypes in the bladder wall were measured using RT‐PCR. Histological studies of bladder specimen were also performed.Results: Weights of BOO bladders were significantly (p < 0.0001) larger compared with sham bladders. In CMG, a number of non‐voiding contractions (NVCs), bladder contraction amplitudes during voiding, bladder capacity, and post‐void residual (PVR) were significantly (p < 0.001) increased compared with sham rats. Voiding efficiency (VE) was significantly (p < 0.001) reduced in BOO versus sham rats. Intravesical application of CCPA or inosine did not induce statistically significant effects on CMG parameters in BOO rats. Yet, ZM241385 induced a significant (p = 0.040) reduction in NVCs of BOO rats. mRNA levels of adenosine A2A and A3 receptors were significantly (p < 0.0001 and p = 0.0145, respectively) upregulated in the BOO bladder mucosa, whereas adenosine A2B receptors showed a significant (p < 0.0001) reduction in the BOO bladder mucosa compared with sham bladders. Histologically, we found the thickened detrusor muscle layer in BOO versus sham rats.Conclusions: The male rat model of BOO seems to be suitable for exploring urethral obstruction‐related bladder dysfunction at the compensated phase. In addition, the adenosine A2A receptor subtype would be a potential target for the treatment of male BOO patients with bladder overactivity.Clinical Trial Registration: A clinical trial registration is not required as this study reported the basic research data using animal models.

Purpose: To investigate the effectiveness of acotiamide on lower urinary tract dysfunction by using a rat model of neurogenic underactive bladder induced through pelvic nerve crush (PNC) injury.Methods: Bilateral PNC injuries were performed on 8-week-old female Sprague-Dawley rats (PNC group); the sham surgery group was used as control (control group). Two weeks after surgery, awake cystometrography (CMG) was performed, and acotiamide (10 or 100 mg/kg) was subcutaneously administered to the control and PNC groups. Subsequently, CMG parameter values obtained before and after treatment were compared.Results: In baseline CMG, compared to control group, PNC group revealed statistically significant elevations in the intercontraction intervals (ICIs), number of nonvoiding contractions, baseline pressure, threshold pressure, bladder capacity, voided volumes, and postvoid residual. However, contraction amplitudes and voiding efficiency were significantly decreased. In the control group, compared with the baseline values, 10-mg/kg acotiamide resulted in statistically significant elevations in contraction amplitudes. Treatment with 100-mg/kg acotiamide led to statistically significant elevations in contraction amplitudes and decreases in ICI and bladder volume. In the PNC group, there were no statistically significant changes noted in CMG parameters after treatment with 10-mg/kg acotiamide (n=6). Compared with the baseline values, the administration of 100-mg/kg acotiamide significantly decreased ICI (1,025±186 seconds vs. 578±161 seconds; P=0.012), bladder capacity (1,841±323 µL vs. 871±174 µL, respectively; P=0.0059) and postvoid residual (223±46 µL vs. 44±22 µL, respectively; P=0.023), and increased contraction amplitudes (22.09±1.76 cm H2O vs. 43.84±6.87 cm H2O, respectively; P=0.012) and voiding efficiency (0.87±0.02 vs. 0.94±0.03, respectively; P=0.029).Conclusions: Acotiamide showed effectiveness in the treatment of underactive bladder, possibly through activation of bladder afferent and detrusor activities.